Cu-Ag alloy wire

Abstract

The present invention provides a Cu-Ag alloy wire which achieves excellent flex fatigue resistance characteristics, while having high tensile strength and high electrical conductivity. The present invention provides a Cu-Ag alloy wire which has a chemical composition that contains 1.0 to 6.0% by mass of Ag, with the balance being made up of Cu and unavoidable impurities; this Cu-Ag alloy wire has a plurality of Ag phases that are linked in the generally longitudinal direction of the Cu-Ag alloy wire, thereby being linearly distributed in the matrix; and the average crystal grain size of the matrix is within the range of 10 to 60 nm as determined in a cross-section that is perpendicular to the longitudinal direction of the Cu-Ag alloy wire.

Description

【Technical Field】 【0001】 The present invention relates to a Cu-Ag alloy wire. 【Background Art】 【0002】 Currently, the wire used for connection cables and the like in electric and electronic devices is becoming thinner in wire diameter. As the wire, instead of a pure Cu wire with insufficient strength, Cu alloy wires such as Cu-Sn-based, Cu-Cr-based, and Cu-Ag-based are likely to be used. However, due to the miniaturization of electronic and electrical equipment products, the space saving of wire installation areas, the increase in signal wiring lines, etc., the wire diameter of the wire tends to become even thinner than before. Among copper alloy wires, a Cu-Ag alloy wire can be cited as a copper alloy wire having a relatively high tensile strength and a relatively high conductivity. 【0003】 For example, in Patent Document 1, a method for producing a copper alloy having high strength and high conductivity is disclosed by stretching the eutectic phase of Cu and Ag in a filament shape. However, in Patent Document 1, there is a problem that the strength characteristics are insufficient because the control of the precipitation distribution contributing to the strength after wire drawing is inappropriate. Also, in Patent Document 2, a Cu-Ag alloy fine wire that develops a recrystallized grain structure by heat treatment during the process and is strengthened to high strength by high processing thereafter is disclosed. However, in Patent Document 2, since appropriate wire drawing process conditions are not adopted before heat treatment, material embrittlement during heat treatment progresses and it becomes difficult to make it thinner, and there is a problem that it cannot be a product with cost competitiveness due to its poor productivity. Also, in Patent Document 3, a Cu-Ag alloy wire capable of having a high tensile strength and a high conductivity is disclosed by the uniform dispersion of some of the Ag crystal precipitates as very fine granular Ag. However, in Patent Document 3, although the distribution of predetermined Ag crystal precipitates is defined, there is a problem that even if the presented manufacturing method is traced to obtain a desired structure, it is not always possible to obtain a high tensile strength and a high conductivity in good balance. 【Prior Art Documents】 [Patent Documents] 【0004】 [Patent Document 1] Patent No. 3325639 [Patent Document 2] Patent No. 5051647 [Patent Document 3] Patent No. 5713230 [Overview of the Initiative] [Problems that the invention aims to solve] 【0005】 Therefore, Patent Documents 1 to 3 all suffer from insufficient control of the metal structure, and have problems in that they do not adequately consider how to ensure the drawability necessary for further thinning compared to conventional Cu-Ag alloy wires, or how to manufacture ultra-fine wires (Cu-Ag alloy wires) that possess both high strength and high conductivity in a well-balanced manner. In addition, there is also the problem that no consideration has been given to improving the properties of the thinner Cu-Ag alloy wires, specifically how to improve their resistance to fracture due to fatigue under conditions of repeated bending (flexural fatigue resistance). Therefore, the object of the present invention is to provide a Cu-Ag alloy wire that possesses high tensile strength and high conductivity, while also exhibiting excellent bending fatigue resistance. [Means for solving the problem] 【0006】 To achieve the above objective, the gist of the present invention is as follows. (1) A Cu-Ag alloy wire having a chemical composition containing 1.0 to 6.0 mass% Ag, with the remainder being Cu and unavoidable impurities, wherein the Cu-Ag alloy wire has a plurality of Ag phases distributed in the matrix phase in a linear manner that is connected substantially along the longitudinal direction of the Cu-Ag alloy wire, and the average crystal grain size of the matrix phase measured in a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire is in the range of 10 to 60 nm. (2) The Cu-Ag alloy wire as described in (1), wherein the product of the average diameter (nm) of the Ag phase and the average grain size (nm) of the matrix phase measured in the cross-section is less than 60 times the Ag content (mass%) in the Cu-Ag alloy wire. (3) The Cu-Ag alloy wire according to (1) or (2), wherein the Cu-Ag alloy wire further contains at least one component selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr, each in an amount of 0.05 to 0.30 mass%. (4) The Cu-Ag alloy wire is a round wire having a diameter of 0.01 mm to 0.08 mm, as described in any one of (1) to (3). (5) The Cu-Ag alloy wire is a ribbon wire having a width of 0.02 to 0.32 mm and a thickness of 0.002 to 0.040 mm, with a substantially rectangular cross-section, as described in any one of (1) to (3). [Effects of the Invention] 【0007】 The present invention provides a Cu-Ag alloy wire that possesses high tensile strength and high conductivity while also exhibiting excellent bending fatigue resistance. This enables miniaturization of electrical and electronic equipment, space savings in the wire installation area, and an increase in signal wiring lines, which were previously impossible, thereby contributing to the creation of high added value for miniaturized electrical and electronic products. [Brief explanation of the drawing] 【0008】 [Figure 1] Figure 1 shows a substantially conical sample prepared from a Cu-Ag alloy wire, which is one embodiment of the present invention. The Ag phase is measured at the tip of the prepared sample, from a first position (0 nm position) corresponding to the tip to a second position (140 nm position) corresponding to a length of 140 nm. The data obtained using a 3DAP device shows the isoconcentration surface of the Ag phase where the Ag atomic concentration is 2.0 atomic%, measured from the side of the tip of the sample. [Figure 2]Figure 2 shows the same data obtained as in Figure 1, and is a diagram of the isoconcentration surface of the Ag phase with an Ag atom concentration of 3.5 atomic percent, when the lower part of the tip of the sample, from the third position (80 nm position) to the second position (140 nm position), which corresponds to a length of 80 nm from the first position, was measured from the upper surface. [Figure 3] Figure 3 is a diagram showing the extension direction and number of each Ag phase, derived from the isoconcentration surface results of the Ag phase shown in Figure 1. [Figure 4] Figure 4 shows the spatial relationships (and average diameters) between adjacent Ag phases, derived from the isoconcentration surface results of the Ag phase shown in Figure 2. [Figure 5] Figure 5 is a bright-field (BF) image of the microstructure in a cross-section perpendicular to the longitudinal direction of a Cu-Ag alloy wire, observed using a scanning transmission electron microscope (STEM). [Modes for carrying out the invention] 【0009】 Embodiments of the present invention are described below. Note that the following description is an example of embodiments of this invention and does not limit the scope of these claims. 【0010】 This document describes a Cu-Ag alloy wire relating to one embodiment of the present invention. A Cu-Ag alloy wire according to one embodiment of the present invention is a Cu-Ag alloy wire having a chemical composition in which 1.0 to 6.0 mass% of Ag is contained and the remainder consists of Cu and unavoidable impurities, wherein the Cu-Ag alloy wire has a plurality of Ag phases distributed in the matrix phase in a linear manner that is connected substantially along the longitudinal direction of the Cu-Ag alloy wire, and the average crystal grain size of the matrix phase measured in a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire is in the range of 10 to 60 nm. 【0011】 (chemical composition) In the Cu-Ag alloy wire of the present invention, 1.0 to 6.0% by mass of Ag is contained. Therefore, Ag is an essential additive component. Ag exists in a state dissolved in Cu, which is the matrix phase (the first phase), or in a state precipitated as an Ag layer that becomes the second phase during the casting of the Cu-Ag alloy wire, and exhibits the effect of solid solution strengthening or dispersion strengthening. 【0012】 When the content of Ag is less than 1.0% by mass, the precipitation of the Ag phase does not occur sufficiently and the desired metal structure cannot be obtained, resulting in insufficient tensile strength, and sufficient flexural fatigue resistance characteristics cannot be obtained either. On the other hand, when the content of Ag exceeds 6.0% by mass, there is no difference in the effects on tensile strength and flexural fatigue resistance characteristics compared to those with 6.0% by mass or less, and the cost increases due to the increased amount of Ag added. From the above, in order to obtain excellent tensile strength and flexural fatigue resistance characteristics and good cost performance even in a Cu-Ag alloy wire of an ultra-fine wire with a smaller diameter without impairing the conductivity, in the present invention, the content of Ag is set to 1.0 to 6.0% by mass. Furthermore, when paying more attention to the balance characteristics of the conductivity in a wide range of applications, the Ag content is more preferably 1.0 to 4.5% by mass. 【0013】 Furthermore, the Cu-Ag alloy wire according to an embodiment of the present invention preferably contains at least one component selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr in the range of 0.05 to 0.30% by mass as optional additive components. These optional additive components all exist mainly in a state dissolved in Cu, which is the matrix phase, and like the case of Ag, are elements that exhibit the effect of solid solution strengthening or dispersion strengthening. Also, by containing them together with the Ag phase, they exist as a second phase of a ternary system or more, such as a Cu-Ag-Zr system, and contribute to further solid solution strengthening or dispersion strengthening. 【0014】 The content of each individual component will be described below. <Sn: 0.05 to 0.30% by mass> When the Sn (tin) content is 0.05 mass% or more, it contributes to the improvement of the strength of the copper alloy wire, and when the Sn content is 0.30 mass% or less, the conductivity is not significantly impaired. Therefore, the Sn content is 0.05 mass% or more, preferably 0.07 mass% or more, more preferably 0.08 mass% or more, and particularly preferably 0.10 mass% or more. On the other hand, the Sn content is 0.30 mass% or less, more preferably 0.18 mass% or less, further preferably 0.15 mass% or less, and particularly preferably 0.12 mass% or less. 【0015】 <Mg: 0.05 - 0.30 mass%> When the Mg (magnesium) content is 0.05 mass% or more, it contributes to the improvement of the strength of the copper alloy wire and has the effect of alleviating the brittleness of the copper alloy wire. When the Mg content is 0.30 mass% or less, the conductivity and manufacturability during casting of the copper alloy wire are not significantly impaired. Therefore, the Mg content is 0.05 mass% or more, preferably 0.07 mass% or more, more preferably 0.08 mass% or more, and particularly preferably 0.10 mass% or more. On the other hand, the Mg content is 0.30 mass% or less, preferably 0.18 mass% or less, further preferably 0.15 mass% or less, and particularly preferably 0.12 mass% or less. 【0016】 <Zn: 0.05 - 0.30 mass%> When the Zn (zinc) content is 0.05 mass% or more, it contributes to the improvement of the strength of the copper alloy wire and has the effect of alleviating the brittleness of the copper alloy wire. When the Zn content is 0.30 mass% or less, the conductivity of the copper alloy wire is not significantly impaired. Therefore, the Zn content is 0.05 mass% or more, preferably 0.07 mass% or more, more preferably 0.08 mass% or more, and particularly preferably 0.10 mass% or more. On the other hand, the Zn content is 0.30 mass% or less, more preferably 0.25 mass% or less, further preferably 0.20 mass% or less, and particularly preferably 0.15 mass% or less. 【0017】 <In: 0.05 - 0.30 mass%> When the indium (In) content is 0.05% by mass or more, it contributes to the improvement of the strength of the copper alloy wire. When the In content is 0.30% by mass or less, the conductivity is not significantly impaired. Therefore, the In content is preferably 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more. On the other hand, the In content is 0.30% by mass or less, preferably 0.18% by mass or less, more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less. 【0018】 <Ni: 0.05 - 0.30% by mass> When the nickel (Ni) content is 0.05% by mass or more, it has an effect of contributing to the improvement of the strength of the copper alloy wire. When the Ni content is 0.30% by mass or less, the conductivity of the copper alloy wire is not significantly impaired. Therefore, the Ni content is 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more. On the other hand, the Ni content is 0.30% by mass or less, preferably 0.25% by mass or less, more preferably 0.20% by mass or less, and particularly preferably 0.15% by mass or less. 【0019】 <Co: 0.05 - 0.30% by mass> When the cobalt (Co) content is 0.05% by mass or more, it contributes to the improvement of the strength of the copper alloy wire. When the Co content is 0.30% by mass or less, the conductivity is not significantly impaired. Therefore, the Co content is 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more. On the other hand, the Co content is 0.30% by mass or less, preferably 0.18% by mass or less, more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less. 【0020】 <Zr: 0.05 - 0.30% by mass> When the content of Zr (zirconium) is 0.05% by mass or more, it contributes to the improvement of the strength of the copper alloy wire and has the effect of alleviating the brittleness of the copper alloy wire. When the content of Zr is 0.30% by mass or less, it does not significantly impair the conductivity and manufacturability during casting of the copper alloy wire. Therefore, the content of Zr is 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more. On the other hand, the content of Zr is 0.30% by mass or less, preferably 0.20% by mass or less, more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less. 【0021】 <Cr: 0.05 to 0.30% by mass> When the content of Cr (chromium) is 0.05% by mass or more, it contributes to the improvement of the strength of the copper alloy wire, and when the content of Cr is 0.30% by mass or less, it does not significantly impair the conductivity. Therefore, the content of Cr is 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more. On the other hand, the content of Cr is 0.30% by mass or less, preferably 0.18% by mass or less, more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less. 【0022】 <Optional additive components: total 0.05 to 1.0% by mass> On the other hand, it is preferable that the above optional additive components are contained in a total range of 0.05 to 1.0% by mass. When the content is less than 0.05% by mass, the decrease in conductivity is small, but it does not contribute to high tensile strength. Also, when the content exceeds 1.0% by mass, the tensile strength becomes very large, but the decrease in conductivity is large and the characteristics of high conductivity cannot be maintained. Therefore, it is preferable that the above optional additive components are contained in a total range of 0.05 to 1.0% by mass. More preferably, it is more preferably contained in a range of 0.1 to 0.5% by mass. 【0023】 <Balance: Cu and inevitable impurities> The remainder of the components other than those listed above consists of Cu and unavoidable impurities. Cu is the matrix phase of the Cu-Ag alloy wire of the present invention, and essential additive components such as Ag exist in a solid solution state or precipitated state. Unavoidable impurities are impurities that are inevitably present at a content level during the manufacturing process of the Cu-Ag alloy wire of the present invention. Depending on the content, unavoidable impurities can cause a decrease in conductivity. Therefore, considering the decrease in conductivity, it is preferable to suppress the content of unavoidable impurities. Examples of unavoidable impurities include Pb, S, P, etc. 【0024】 The microstructure of the Cu-Ag alloy wire of the present invention is described below. A Cu-Ag alloy wire according to one embodiment of the present invention has a plurality of Ag phases distributed in the matrix phase in a linear manner that is connected substantially along the longitudinal direction of the Cu-Ag alloy wire, and the average grain size of the matrix phase measured in a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire is in the range of 10 to 60 nm. 【0025】 The Ag phase is measured using the three-dimensional atom probe method (3DAP method). Figures 1-4 show the state of the Ag phase in the matrix of a Cu-Ag alloy wire, which is one embodiment of the present invention, as measured by the 3DAP method. These microstructures allow us to observe the state of Ag present in the matrix of the Cu-Ag alloy wire using the 3DAP method. 3DAP is an analytical technique that allows for three-dimensional compositional analysis of nanodeposits and clusters in metals and semiconductors. The principle is as follows: A needle-shaped sample with a diameter of approximately 100 nm and a roughly conical tip is prepared and loaded into a 3D atom probe field-ion microscope (3DAP). A high voltage is then pulsed to evaporate atoms one by one from the tip of the sample. Additionally, irradiating the tip of the needle with a pulsed laser of a specific wavelength assists the field evaporation, reducing the probability of sample damage, improving mass resolution, and enabling the measurement of semiconductors and insulators. The time of flight and position of ions evaporated by pulsed voltage and laser irradiation are detected by a 2D position detector, determining the 2D coordinate position of each ion. By measuring the time from evaporation at the tip of the needle to arrival at the detector, analysis as time-of-flight mass spectrometry is also possible, allowing identification of the ion species that arrived. By repeatedly irradiating with laser, information on the 2D coordinate position of the ions and information on the depth of the sample can be obtained. By performing data analysis considering the shape of the needle tip, 3D compositional information can be obtained. 【0026】 Here are some representative results measured using the 3DAP method. Figure 1 shows data obtained using a 3DAP device, showing the isoconcentration surface of the Ag phase at the tip of the prepared sample, from a Cu-Ag alloy wire (Ag concentration: 2.0 mass%), which is one embodiment of the present invention. The data shows the Ag phase at the tip of the sample, from a first position (0 nm position) corresponding to the tip to a second position (140 nm position) corresponding to a length of 140 nm, with the Ag atomic concentration being 2.0 atomic percent when the tip of the sample is measured from the side. Figure 2 shows the same data obtained as in Figure 1, and illustrates the isoconcentration surface of the Ag phase with an Ag atom concentration of 3.5 atomic percent, measured from the top surface on the lower part of the tip of the sample, from the third position (80 nm position), which corresponds to a length of 80 nm from the first position, to the second position (140 nm position). Figure 3 shows the results obtained by graphically determining the extension direction and number of each Ag phase based on the isoconcentration surface of the Ag phase shown in Figure 2. Figure 4 shows the result of graphically representing the spacing (and average diameter) between adjacent Ag phases, based on the isoconcentration surface results of the Ag phase shown in Figure 2. 【0027】 The 3DAP method involves setting an Ag threshold for the same concentration as the Ag concentration in a cross-section perpendicular to the longitudinal direction of a Cu-Ag alloy wire. Areas where a concentration distribution exceeding this threshold is observed are provisionally designated as the Ag phase. This allows for the measurement of an image of the Ag phase with atomic concentrations exceeding the predetermined threshold, as seen from the longitudinal direction, as shown in Figure 1. Furthermore, as shown in Figure 2, an image of the Ag phase with atomic concentrations exceeding the predetermined threshold, as seen from the cross-sectional direction, can also be measured. 【0028】 Furthermore, to identify the Ag phase in this case, as shown in Figure 2, the Ag identified when the Ag isoconcentration surface of 3.5 at% was set as the threshold was assigned, and the number of phases was counted. 【0029】 Corresponding to the previously provisional Ag phase, profile analysis was performed along the longitudinal direction, and the Ag phase was selected as the one having a continuous Ag atom concentration of 0.5 to 50.0% over a length of 60 nm. Figures 3 and 4 show the results of this analysis; Figure 3 shows the result of assigning the Ag phase along the longitudinal direction of the line, and Figure 4 shows the result of assigning the Ag phase from a cross-sectional view of the line. Furthermore, the average diameter of the Ag phase was calculated by assuming the Ag phase was a perfect circle from a cross-section perpendicular to the longitudinal direction of the selected Ag phase, and then calculating the average diameter from the area. This series of analyses can be performed using IVAS, the 3DAP software provided by CAMECA. 【0030】 Figure 1 shows the isoconcentration surface of the Ag phase at the tip of a substantially conical sample prepared from a Cu-Ag alloy wire (Ag concentration: 2.0 mass%), which is one embodiment of the present invention. The Ag phase was measured from the first position (0 nm position), corresponding to the tip, to the second position (140 nm position), corresponding to a length of 140 nm, using a 3DAP device. The data shows the Ag phase with an Ag atom concentration of 2.0 atomic percent when the tip of the sample is measured from the side. Figure 2 shows the isoconcentration surface of the Ag phase with an Ag atom concentration of 3.5 atomic percent, obtained in the same manner as in Figure 1. The lower part of the tip of the sample, from the third position (80 nm position), corresponding to a length of 80 nm from the first position, to the second position (140 nm position), measured from the top surface. Figure 3 shows the diagram obtained by graphically determining the extension direction and number of each Ag phase from the results of the Ag phase isoconcentration surface shown in Figure 2. Figure 4 shows the average diameter of the Ag phase, calculated graphically from the isoconcentration surface results of the Ag phase shown in Figure 2. 【0031】 The Cu-Ag alloy wire of the present invention has multiple Ag phases distributed linearly in the matrix phase, extending approximately along the longitudinal direction of the Cu-Ag alloy wire. As can be seen in Figures 1 and 3, the Ag phases are not perfectly aligned in the longitudinal direction, but are approximately parallel and extend along the longitudinal direction of the wire. Furthermore, the Ag phases have an Ag atom concentration of 0.5 to 50.0% and are phases that extend along the longitudinal direction. Here, "phases that extend along the longitudinal direction" means that the Ag atom concentration does not form a uniform phase with a constant value in the longitudinal direction, but rather the phase is formed with an Ag atom concentration fluctuating between 0.5 and 50.0%. Here, the atomic concentration indicates the proportion of Ag present, and if it is less than 0.5%, it is not possible to distinguish whether Ag is precipitated or in solid solution, and the second phase cannot be determined. Also, if it exceeds 50.0%, the Ag phase becomes sufficiently coarse, and the interphase spacing tends to become sparse, making it impossible to obtain high tensile strength. Therefore, the Ag phase must have an Ag atom concentration within the range of 0.5 to 50.0 atomic percent. Furthermore, if the Ag phases are not continuous in the longitudinal direction, the spacing between Ag phases will become sparse, and it will not be possible to increase the tensile strength and bending fatigue resistance. Therefore, the Ag phases form multiple Ag phases that are distributed linearly, continuously in approximately the longitudinal direction of the Cu-Ag alloy wire. 【0032】 Furthermore, the average diameter of the Ag phase, when measured in a cross-section perpendicular to the longitudinal direction, is preferably in the range of 0.5 to 20 nm. If the average diameter of the Ag phase is less than 0.5 nm, it is almost the same size as the atomic diameter, making it difficult to determine the solid solution or precipitate state of Ag with the resolution of existing analytical instruments. On the other hand, specifying a range of 0.5 nm or more allows for sufficient clarification of the relationship with the properties, so this is set as a lower limit. Diameters larger than 20 nm have a low abundance and wide phase spacing, so they hardly contribute to density. For this reason, the improvement in tensile strength and flexural fatigue resistance is negligible, so there is no need to consider the presence of particles larger than 20 nm. Therefore, the Cu-Ag alloy wire of the present invention is measured using a 3DAP device and analyzed using IVAS, and the phase in which the Ag atom concentration is in the range of 0.5 to 50.0 atomic percent and the average diameter is in the range of 0.5 to 20 nm is defined as the Ag phase. 【0033】 Furthermore, the microstructure of these metals is observed by scanning transmission electron microscopy (STEM) using the grain size of Cu-Ag alloy wires. STEM is a device that irradiates a thinned sample with an electron beam, capturing the electron information transmitted through the sample and enabling high-magnification, high-resolution observation of atomic and molecular images at a level where they can be directly observed. By irradiating the sample with an extremely focused electron beam, STEM can image the atomic distribution, morphology, composition, and crystal structure within the sample. Furthermore, STEM can capture atomic images and the structure of materials at the sub-nm order. 【0034】 Samples for STEM observation were prepared using the Focused Ion Beam (FIB) method. A SIINT-3050TB was used, and the Ga ion beam was accelerated to 30kV. To remove damage from the FIB, Ar ion milling at 2kV was performed for 5 minutes after FIB thin film processing. STEM observation was performed using a JEOL ARM with aberration correction capabilities. The electron beam was accelerated to 200kV. Brightfield (BF) and high-angle annular dark field (HAADF) imaging were performed during STEM observation. Elemental analysis was performed using energy-dispersive X-ray spectroscopy (EDX), which is attached to the STEM. The average grain size of the matrix phase was determined using the sectioning method (JIS H 0501) from the bright-field (BF) images (BF) of the obtained line cross-sections. The number of grains that were completely cut by line segments of known length, regardless of direction, was counted on the image, and the average length of these sections (nm) was used as the value. 【0035】 Figure 5 is a bright-field (BF) image showing the microstructure of a Cu-Ag alloy wire in a cross-section perpendicular to the longitudinal direction, as observed by STEM. The scale shown in Figure 5 is 20 nm. As shown in Figure 5, the Cu-Ag alloy wire of the present invention has an average grain size of the matrix phase measured in a cross-section perpendicular to the longitudinal direction, which is in the range of 10 to 60 nm. 【0036】 Therefore, conventional Cu-Ag copper alloy wires typically have an average grain size of the matrix phase on the submicron order (0.1 μm or larger), and are generally at least greater than 60 nm. However, the Cu-Ag copper alloy wire of the present invention has an average grain size in the range of 10 to 60 nm. The matrix phase mainly consists of Cu and solid-solution Ag, and while the effect on properties is not discernible when the average grain size observed from the cross-section is less than 10 nm, this was not confirmed within the range of the present invention. When the average grain size is within this range, the grain boundaries play a role in suppressing and accumulating dislocation movement, contributing to improved strength (Hall-Petch law). Above 60 nm, the tensile strength ultimately decreases. While the average grain size has conventionally been quite coarse, the Cu-Ag copper alloy wire of the present invention achieves high tensile strength and flexural fatigue resistance that were previously unattainable by controlling the grain size within the range of 10 to 60 nm. In detail, when the grain size is large, the amount of deformation carried out by a single grain is large, so shear deformation progresses within the grain and shear bands develop strongly. Stress concentration at the grain boundaries, which are fragile due to the large amount of precipitation, becomes significant, creating a situation where cracks are likely to occur at the grain boundaries, and grain boundary cracks occur when the grain size is large, degrading the flexural fatigue resistance. Even if the strength of the matrix is ​​high, when the grain size is small, the deformation at a single grain is small, the development of shear bands is suppressed, and the stress at the grain boundaries is also distributed, so good flexural fatigue resistance can be maintained. Therefore, in order to obtain good flexural fatigue resistance, the average grain size needs to be 10 to 60 nm. 【0037】 In this way, by keeping the average grain size of the matrix phase within a certain range, a Cu-Ag alloy wire with excellent bending fatigue resistance was obtained. Furthermore, in order to obtain high tensile strength, it is necessary to either sufficiently solid dissolve Ag in the Cu matrix phase at high temperatures, or to form an Ag phase by finely precipitating Ag in the Cu matrix phase. In other words, by controlling both the average diameter (nm) of the Ag phase and the average grain size (nm) of the matrix phase, it is possible to achieve both high tensile strength and excellent bending fatigue resistance. Specifically, in the Cu-Ag alloy wire of the present invention, it is preferable that the product of the average diameter (nm) of the Ag phase and the average grain size (nm) of the matrix phase measured in cross-section (hereinafter sometimes simply referred to as "the product value") is smaller than 60 times the Ag content (mass%) in the Cu-Ag alloy wire. When the product value is smaller than 60 times the Ag content (mass%) in the Cu-Ag alloy wire, the average diameter of the Ag phase and the average grain size of the matrix phase are fine, resulting in sufficient strength and flexural fatigue resistance. In particular, if the average grain size of the matrix phase is in the range of 10 to 60 nm, the flexural fatigue resistance is further improved. On the other hand, when the product value is greater than or equal to 60 times the Ag content (mass%) in the Cu-Ag alloy wire, the Ag phase is very coarse relative to the grain size of the matrix phase, and the tensile strength tends to decrease. Therefore, the Cu-Ag alloy wire of the present invention has a product value smaller than 60 times the Ag content (mass%) in the Cu-Ag alloy wire. Until now, it has been difficult to manufacture the matrix phase with fine grain size, and it has also been difficult to precipitate the Ag phase finely in the matrix phase. The Cu-Ag alloy wire of the present invention can control both the average diameter (nm) of the Ag phase and the average grain size (nm) of the matrix phase, as measured in cross-section, to be reduced in a balanced manner. 【0038】 Currently, Cu-Ag alloy wires are increasingly being made thinner in diameter, and ultra-fine wires are frequently being used. Therefore, high tensile strength and high bending fatigue resistance are required. The Cu-Ag alloy wire of the present invention, by adopting the above-described metal structure, can achieve a tensile strength of at least 900 MPa, more preferably 1000 MPa or more. Therefore, even with a thin wire diameter, a high-strength Cu-Ag alloy wire can be obtained. Furthermore, the use of ultra-fine wires requires high conductivity. The Cu-Ag alloy wire of the present invention can achieve a conductivity of at least 65% IACS, and more preferably 75% IACS, by suppressing the amount of additive elements and optional additive elements. 【0039】 Furthermore, the Cu-Ag alloy wire of the present invention is a round wire with a diameter of 0.01 mm to 0.08 mm and a substantially circular cross-section. Even for ultra-fine wires (Cu-Ag alloy wires) with a diameter of 0.01 mm to 0.08 mm, it is desirable that they possess high tensile strength and high conductivity. Cu-Ag alloy wires with a diameter of less than 0.01 mm cannot be said to meet sufficient user needs. On the other hand, Cu-Ag alloy wires with a diameter exceeding 0.08 mm cannot fulfill their role as ultra-fine wires. Furthermore, the Cu-Ag alloy wire may also be a ribbon wire having a ribbon shape that is not substantially circular in cross-section but substantially rectangular. For the same reasons as the upper and lower limits of the wire diameter, the dimensions of the ribbon shape are preferably 0.02 to 0.32 mm in width and 0.002 to 0.040 mm in thickness. As for the manufacturing method, for example, the above-mentioned round wire, which has been drawn, can be rolled to form the desired shape. The plate width corresponds to the width direction of the rolling roll, and the plate thickness corresponds to the direction between the rolls, and the non-contact portion of the rolling rolls at the end in the width direction retains a shape that maintains an arc while deforming. Here, in the cross-section of the ribbon wire, the longer value is defined as the width and the shorter value as the thickness. 【0040】 The method for manufacturing the Cu-Ag alloy wire of the present invention will be described below. However, the manufacturing method described is just one example of how to manufacture the present invention, and the manufacturing method is not limited to this method. The present invention provides a method for manufacturing Cu-Ag alloy wire, comprising: a casting step of melting and casting a Cu-Ag alloy material having the above-described chemical composition and cooling it to obtain an ingot; a first wire drawing step of drawing the Cu-Ag alloy material obtained from the ingot; a first heat treatment step of heat treating the drawn Cu-Ag alloy material; a second heat treatment step; and a second wire drawing step of performing a final wire drawing to obtain a Cu-Ag alloy wire. A stress-relieving annealing treatment can be performed during the wire drawing process in this second wire drawing step. 【0041】 (Casting process) In the casting process, the cooling rate is set to 10°C / second or higher to prevent excessive formation of Ag crystals in the Cu matrix during cooling. If the amount of crystals formed during casting is large, the Ag phase will not be formed to the appropriate diameter even after subsequent wire drawing, resulting in larger gaps between the Ag phases and a decrease in the tensile strength of the final Cu-Ag alloy wire. 【0042】 (1st wire drawing process) Next, the first wire drawing process is performed after the casting process and before the heat treatment process. A processing rate of 50-90% is desirable to promote sufficient precipitation of Ag during heat treatment. If the processing rate is less than 50%, sufficient precipitation will not be generated, and the increase in strength relative to the processing rate in the subsequent second wire drawing process will be small. This is because Cu-Ag alloy wires tend to have insufficient strength at larger diameters, making it difficult to obtain high tensile strength. On the other hand, while precipitation is promoted with a wire drawing rate of 90% or more, it becomes difficult to obtain high tensile strength because a high processing rate cannot be taken in the subsequent wire drawing process after heat treatment. Therefore, it is desirable to set an upper limit of 90%. The processing rate is defined as ((S1-S2) / S1) × 100 (%), where S1 is the cross-sectional area before wire drawing and S2 is the cross-sectional area after wire drawing. 【0043】 (First heat treatment process) → (Second heat treatment process) Next, the first heat treatment process involves introducing at least two heat treatment steps while drawing the ingot to its final diameter. The aim of this heat treatment is the precipitation of Ag. The first heat treatment step is held at a temperature in the range of 350 to 450°C, and the second heat treatment step is held at a temperature of 250 to 375°C, for a total of 10 to 50 hours. The second heat treatment step must be performed at a temperature at least 25°C lower than the first heat treatment step. By introducing a second heat treatment step at a lower temperature than the first heat treatment step, a large amount of Ag phase is precipitated in the first heat treatment step, which has a strong driving force, and the final amount of Ag phase precipitated in the second heat treatment step, where the solid solubility limit is narrowed and the driving force is lower due to the lower temperature. If the heat treatment temperature is low or the treatment time is short, recrystallization does not proceed at this stage, and the Ag phase does not grow. As a result, the average grain size of the matrix phase after the final process cannot be kept within the range of 10 nm to 60 nm, and the product of the average diameter of the Ag phase and the average grain size of the matrix phase tends to be greater than or equal to Ag concentration × 60. Furthermore, if the heat treatment temperature is too high or the treatment time is too long, both the recrystallized grains and the Ag phase become coarse, and in this case as well, the desired final structure cannot be obtained. Controlling the product of the average diameter of the Ag phase and the average grain size of the matrix phase is difficult because the growth driving force for each structure changes significantly depending on the amount of plastic deformation before heat treatment, and the optimal heat treatment conditions also change. Therefore, fine control is necessary to obtain a structure within the scope of the present invention. 【0044】 (Second wire drawing process) Next, in order to fully bring out the strength properties of this alloy, the processing rate in the second wire drawing process should preferably be around 95% to 99.9999%. If the processing rate is too low, neither the grain size of the matrix phase nor the Ag phase will meet the quantities within the size range of the invention, and a sufficient increase in tensile strength will not be achieved. The upper limit of the processing rate is due to practical limitations and does not relate to the properties. In the second wire drawing process, the processing rate per pass should be in the range of 15 to 35%. A processing rate higher than this may cause the wire to break. Furthermore, it was confirmed that, depending on the combination of the preceding wire drawing and heat treatment processes, the tensile strength saturates and, in some cases, decreases as the processing rate increases. The details of this phenomenon are unknown, but it is assumed that changes in the microstructure that contribute to tensile strength, such as dislocation distribution and crystal orientation distribution, are occurring. Continuing the wire drawing process after the tensile strength has saturated often adversely affects the bending fatigue resistance; therefore, it is necessary to apply heat treatment before reaching that stage to suppress the phenomenon. Applying high-temperature, long-duration heating significantly reduces tensile strength, and the tensile strength at the final wire diameter after drawing also decreases; therefore, heat treatment at 200-400°C for 10 minutes to 2 hours is desirable. 【0045】 The ribbon-shaped wire was produced by rolling the circular wire described above to a specified thickness. Depending on the combination of the drawing conditions before heat treatment, the heat treatment conditions, and the final drawing conditions, work hardening may saturate, which can lead to a decrease in strength. When work hardening saturates, it can negatively affect bending fatigue resistance, including twisting, so it is effective to add an intermediate heat treatment aimed at removing strain without causing significant softening. 【0046】 Furthermore, although it does not contribute to the properties, a stripping step can be included in the process to facilitate the wire drawing process. In addition, a final heat treatment step is performed at the end of the manufacturing process to obtain the final Cu-Ag alloy wire (heat-treated product). The conditions for this final heat treatment are not particularly limited, but it is preferable to perform it at a temperature of 450 to 600°C for a time of 10 seconds to 30 minutes. [Examples] 【0047】 The present invention will be described in detail based on the following embodiments. However, the present invention is not limited to the embodiments shown below. 【0048】 In air, Cu-1.5 mass%Ag (Examples 1-1 to 1-12, Comparative Examples 1-1 to 1-11), Cu-2.0 mass%Ag (Examples 2-1 to 2-12, Comparative Examples 2-1 to 2-11), Cu-4.0 mass%Ag (Examples 3-1 to 3-12, Comparative Examples 3-1 to 3-11), Cu-6.0 mass%Ag (Examples 4-1 to 4-12, Comparative Examples 4-1 to 4-11), Cu-0.5 mass%Ag, -0.8 mass%Ag, -6. Cu-Ag alloys having the chemical compositions shown in 5 mass%Ag, -8.0 mass%Ag (Comparative Examples 5-1, 5-2, 5-3, 5-4), and Cu-2.0 mass%Ag-(one component of Sn, Mg, Zn, In, Ni, Co, Zr, or Cr) (Examples 6-1 to 6-8, Comparative Examples 6-1 to 6-3) were melted, cast, and cooled at a cooling rate of 8 to 50°C / second to produce ingots with a diameter of 4.6 to 11.4 mm (casting process). 【0049】 Next, this ingot was drawn to a diameter of 1.0 to 9.5 mmφ with a processing rate of 35 to 95% (first drawing process). Next, an aging heat treatment, which combined precipitation and recrystallization, was performed at 350-550°C for 3-50 hours (first heat treatment step). Next, the mixture was held at a lower temperature, 250-375°C, for 1-60 hours (second heat treatment step). Furthermore, after cooling, cold drawing was performed to reduce the wire diameter to 0.02-0.08 mmφ with a viscosity of 99.7-99.998% (second drawing process). In addition, stress-relieving annealing was performed during the cold drawing process in the second drawing process. 【0050】 (Performance evaluation) The Cu-Ag alloy wires manufactured as described above were subjected to tensile strength, bending fatigue resistance, and, if necessary, electrical conductivity measurements. Furthermore, the microstructure was analyzed using a 3DAP device and analysis software, and the microstructure was observed and analyzed using a STEM and associated EDX. 【0051】 (Tensile strength) Although the tensile strength measurement did not conform to JIS Z2201 because the test specimen shape was the original linear shape, the test conditions conformed to JIS Z2241. Measurements were taken using three test specimens (n=3), and the average value (MPa) of the measured tensile strength was used as the measured value. 【0052】 (Flexural fatigue resistance) The flexural fatigue resistance was evaluated by repeated bending tests in accordance with JIS H 0500 No. 4100. Considering that fatigue characteristics depend on the wire diameter, all tests were conducted using wires with an outer diameter of 0.03 mmφ. The radius R of the jig at the bending support point during bending was set to 6 mm, one end was fixed to a grip, and a 30 g weight was suspended from the other end to prevent bending. The number of cycles until wire breakage was measured, and the average value (average bending life, n=5) was evaluated based on whether it satisfied the relationship between Equations 1 and 2 below. Specifically, if the average bending life value satisfied Equation 1, it was evaluated as having excellent flexural fatigue resistance ("◎"); if it did not satisfy Equation 1 but satisfied Equation 2, it was evaluated as having good flexural fatigue resistance ("〇"); and if it did not satisfy either Equation 1 or Equation 2, it was evaluated as having poor flexural fatigue resistance ("×"). Formula 1: Average bending life ≧5900×(Ag concentration)+40000 Formula 2: Average bending life ≧5900×(Ag concentration)+20000 【0053】 (conductivity) Conductivity was measured using the four-terminal method based on JIS H0505-1975. The conductivity of two wires from each test specimen was measured in a constant temperature bath controlled at 20°C (±1°C), and the average value (%IACS) was taken as the measured value. The distance between terminals was set to 100 mm. 【0054】 (Metal structure) The microstructure of Cu-Ag alloy wires was observed and analyzed using a 3DAP instrument and analysis software, as the second phase Ag phase had a sub-nanometer to nanoscale size. The matrix phase, with a sub-nanometer to nanoscale grain size, was analyzed using a scanning transmission electron microscope (STEM). 【0055】 The 3DAP device visualizes nanometer-order three-dimensional structures by evaporating the material, detecting the evaporated atoms with a two-dimensional detector, and reconstructing the data. Samples for 3D atom probe measurements were prepared using FIB. 【0056】 FIBs used were SIINT-3050TB and HeliosG4 (FEI). Using a Ga ion beam with an acceleration voltage of 30kV, a conical sample with a circular base having a diameter of approximately 80nm and a length of approximately 140nm was fabricated. For the direction of analysis, the longitudinal direction of the Cu-Ag alloy wire was used as the length direction of the sample, but the diametrical direction of the cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire may also be used as the length direction. For the final finishing, a 5kV ion beam was used to reduce the damage layer as much as possible. 【0057】 A LEAP4000XSi (AMETEK) 3DAP system was used. The sample was evaporated using a pulsed laser with a wavelength of 355 nm (ultraviolet light). The voltage applied to the sample was 1-5 kV. Analysis of the atomic concentration and shortest interval of the Ag phase was performed using analysis software such as IVAS 3.8.8 (CAMECA) or IVAS LT. 【0058】 (Average diameter of the Ag phase) In the 3DAP method, an Ag threshold was set for each Ag concentration in a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire. Areas where a concentration distribution exceeding this threshold was observed were provisionally identified as the Ag phase. In relation to the provisional Ag phase, profile analysis was performed along the longitudinal direction, and the Ag phase was selected as the one that continuously had an Ag atom concentration of 0.5 to 50.0% over a length of 60 nm. The average diameter of the Ag phase was calculated by assuming the Ag phase is a perfect circle from a cross-section perpendicular to the longitudinal direction of the selected Ag phase, and then calculating the average diameter from the area. 【0059】 STEM observations were performed using an atomic-resolution analytical electron microscope (JEOL ARM: JEM-ARM200F) with aberration correction capabilities. The electron beam acceleration voltage was 200kV. STEM observations were performed in bright-field (BF) and high-angle annular dark-field (HAADF) modes. Elemental analysis was performed using energy-dispersive X-ray spectroscopy (EDX) attached to the TEM in areas where a contrast suggestive of an Ag layer was confirmed. 【0060】 (Average grain size of the matrix phase, average diameter of the Ag phase × average grain size of the matrix phase) The average grain size was calculated from the obtained bright-field (BF) images using the sectioning method. The sectioning method was based on the provisions of JIS H 0501. In cases where the crystal grains of the matrix phase were very fine and difficult to determine using STEM alone, the average value was calculated using the analysis results from a 3DAP device in conjunction with STEM. Next, the numerical value was calculated by multiplying the average diameter of the Ag phase by the average grain size of the matrix phase. 【0061】 (Examples 1-1 to 1-12, Comparative Examples 1-1 to 1-11) Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-11 were prepared using Cu-Ag alloy wire having a chemical composition of Cu-1.5 mass%Ag, by varying the processing rate in the first and second wire drawing processes and the manufacturing conditions in the first and second heat treatment processes. 【0062】 Table 1 shows the manufacturing conditions for Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-11. Note that in Example 1-10, a circular shape with a final diameter of 0.03 mm was processed and formed into a ribbon shape with a thickness of 0.008 mm and a width of 0.08 mm. Note that underlined text in the table indicates that the product is outside the scope of the present invention. [Table 1] 【0063】 Table 2 shows the evaluation results of the microstructure and properties of Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-11. The evaluation items are, as for the metal structure, the average grain size of the matrix phase, the average diameter of the Ag phase, and the product value; and as for mechanical properties, tensile strength and flexural fatigue resistance. Also, 60 times the Ag content (mass%) is "90". [Table 2] 【0064】 As shown in Table 2, in all of Examples 1-1 to 1-12, the average grain size of the matrix phase, the average diameter of the Ag phase, and the product value are within the range of the present invention. The tensile strength of all is high, exceeding 1100 MPa. Furthermore, in Examples 1-5 to 1-6 and 1-11, the product value exceeds 90, which is 60 times the Ag content (mass%), so the flexural fatigue resistance is rated "○". In the other Examples 1-1 to 1-4, 1-7 to 1-10 and 1-12, the product value is within 90, which is 60 times the Ag content (mass%), so the flexural fatigue resistance is rated "◎". Furthermore, the tensile strengths of Comparative Examples 1-1 to 1-11 are all 980 MPa or higher, which is lower than that of Examples 1-1 to 1-12. In addition, the average grain size of the matrix phase is outside the range of the present invention, and the product value is also outside the range of the present invention and is greater than 90, so the flexural fatigue resistance is also marked as "×". 【0065】 (Examples 2-1 to 2-12, Comparative Examples 2-1 to 2-11) Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-11 were prepared using Cu-Ag alloy wire having a chemical composition of Cu-2.0 mass%Ag. 【0066】 Table 3 shows the manufacturing conditions for Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-11. [Table 3] 【0067】 Table 4 shows the evaluation results of the metal structure and properties of Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-11. Note that 60 times the Ag content (mass%) is 120. [Table 4] 【0068】 As shown in Table 4, in all of Examples 2-1 to 2-12, the average grain size of the matrix phase, the average diameter of the Ag phase, and the product value are within the range of the present invention. The tensile strength of all is high, exceeding 1100 MPa. Furthermore, in Examples 2-5 to 2-8 and 2-10 to 2-12, the product value exceeds 120, which is 60 times the Ag content (mass%), so the flexural fatigue resistance is rated "○". In the other Examples 2-1 to 2-4 and 2-9, the product value is within 120, which is 60 times the Ag content (mass%), so the flexural fatigue resistance is rated "◎". In Comparative Examples 2-1 to 2-11, the average grain size and product value of the matrix phase are outside the range of the present invention, and the tensile strength is all 1000 MPa or higher, which is lower than that of Examples 2-1 to 2-12. Also, the product value is greater than 120, and the flexural fatigue resistance is also marked as "×". 【0069】 (Examples 3-1 to 3-12, Comparative Examples 3-1 to 3-11) Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-11 were prepared using Cu-Ag alloy wire having a chemical composition of Cu-4.0 mass%Ag. 【0070】 Table 5 shows the manufacturing conditions for Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-11. [Table 5] 【0071】 Table 6 shows the evaluation results of the microstructure and properties of Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-11. [Table 6] 【0072】 Examples 3-1 to 3-12 all have average grain size of the matrix phase, average diameter of the Ag phase, and product values ​​within the range of the present invention. All of them have high tensile strength of 1300 MPa or more. In addition, Examples 3-2, 3-4 to 3-5, and 3-10 to 3-12 have a product value that exceeds 240, which is 60 times the Ag content (mass%), so their flexural fatigue resistance is rated "〇". The other examples 3-1, 3-3, and 3-6 to 3-9 have a product value that is within 240, which is 60 times the Ag content (mass%), so their flexural fatigue resistance is rated "◎". In Comparative Examples 3-1 to 3-11, the average grain size and product values ​​of the matrix phase are outside the range of the present invention, and the tensile strength is 1000 MPa or higher in all cases, which is lower than that of Examples 3-1 and 3-2. Also, the product value is greater than 240, and the flexural fatigue resistance is also marked as "×". 【0073】 (Examples 4-1 to 4-12, Comparative Examples 4-1 to 4-11) Examples 4-1 to 4-12 and Comparative Examples 4-1 to 4-11 were prepared using Cu-Ag alloy wire having a chemical composition of Cu-6.0 mass%Ag. 【0074】 Table 7 shows the manufacturing conditions for Examples 4-1 to 4-12 and Comparative Examples 4-1 to 4-11. [Table 7] 【0075】 Table 8 shows the evaluation results of the microstructure and properties of Examples 4-1 to 4-12 and Comparative Examples 4-1 to 4-11. [Table 8] 【0076】 Examples 4-1 to 4-12 all have average grain size of the matrix phase, average diameter of the Ag phase, and product values ​​within the range of the present invention. All of them have high tensile strength of 1300 MPa or more. In addition, Examples 4-2, 4-5, and 4-12 have a product value that exceeds 360, which is 60 times the Ag content (mass%), so their flexural fatigue resistance is rated "○". Examples 4-1, 4-3, 4-6 to 4-11 have a product value that is within 360, which is 60 times the Ag content (mass%), so their flexural fatigue resistance is rated "◎". In comparative examples 4-1 to 4-11, the average grain size and product value of the matrix phase are outside the range of the present invention, and the tensile strength is all 1000 MPa or higher, which is lower than that of examples 4-1 to 4-12. Also, the product value is greater than 360, and the flexural fatigue resistance is also marked as "×". 【0077】 (Comparative Examples 5-1 to 5-4) Comparative Examples 5-1 to 5-11 are Cu-Ag alloy wires containing Ag outside the range of the present invention, specifically Cu-Ag alloy wires with chemical compositions of Cu-0.5 mass%Ag, Cu-0.8 mass%Ag, Cu-6.5 mass%Ag, and Cu-8.0 mass%Ag, and samples were prepared using these wires. 【0078】 Table 9 shows the manufacturing conditions for Comparative Examples 5-1 to 5-4. [Table 9] 【0079】 Table 10 shows the evaluation results of the metal structure and properties of Comparative Examples 5-1 to 5-4. [Table 10] 【0080】 However, as shown in Table 10, comparative examples 5-1 and 5-2 have an amount of Ag added that is less than the lower limit of 1.0 mass%, so the precipitation of the Ag phase could not be observed by analysis using a 3DAP instrument. For this reason, the tensile strength is less than 900 MPa, and the flexural fatigue resistance does not satisfy Equation 1, resulting in a "×". Comparative Example 5-3: Since the amount of Ag added was greater than the upper limit of 6.0 mass%, the tensile strength was greater than 900 MPa. Also, since the product value was within 390, which is 60 times the Ag content (mass%), the flexural fatigue resistance is "◎". Comparative Example 5-4: Since the amount of Ag added was greater than the upper limit of 6.0 mass%, the tensile strength was greater than 900 MPa. Also, since the product value was within 480, which is 60 times the Ag content (mass%), the flexural fatigue resistance is "◎". However, comparing Comparative Example 5-3 with Example 4-3, and Comparative Example 5-4 with Example 4-4, there was no difference in the effects on tensile strength and flexural fatigue resistance. Increasing the amount of Ag added only increased the cost without any benefit. 【0081】 (Examples 6-1 to 6-8, Comparative Examples 6-1 to 6-3) Examples 6-1 to 6-8 used Cu-Ag alloy wires having a chemical composition containing Cu-2.0 mass%Ag and one selected from Sn, Mg, Zn, In, Ni, Co, Zr, and Cr, while Comparative Examples 6-1 to 6-3 used Cu-Ag alloy wires having a chemical composition containing Cu-2.0 mass%Ag and 0.5 mass% of Sn, Mg, and Zr, respectively, to prepare samples. 【0082】 Table 11 shows the manufacturing conditions for Examples 6-1 to 6-8 and Comparative Examples 6-1 to 6-3. [Table 11] 【0083】 Table 12 shows the evaluation results of the microstructure and properties of Examples 6-1 to 6-8 and Comparative Examples 6-1 to 6-3. [Table 12] 【0084】 Examples 6-1 to 6-8 all have average grain size of the matrix phase, average diameter of the Ag phase, and product values ​​that are within the range of the present invention. All of them have a high tensile strength of 1100 MPa or more. In addition, since the product value of Examples 6-1 to 6-8 is within 120, which is 60 times the Ag content (mass%), the bending fatigue resistance is excellent. Furthermore, Comparative Example 6-1 contains 0.5 mass% Sn, and Comparative Example 6-2 contains 0.5 mass% Mg, resulting in low conductivity and practical problems. In addition, Comparative Example 6-3 contains 0.5 mass% Zr, which causes ingot cracking during manufacturing, making it difficult to produce round wires and other products, thus posing manufacturing problems.

Claims

[Claim 1] A Cu-Ag alloy wire having a chemical composition containing 1.0 to 6.0 mass% Ag, with the remainder being Cu and unavoidable impurities, The Cu-Ag alloy wire has a plurality of Ag phases distributed in the matrix phase in a linear manner that is connected substantially along the longitudinal direction of the Cu-Ag alloy wire. A Cu-Ag alloy wire wherein the average grain size of the matrix phase, measured in a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire, is in the range of 10 to 60 nm. [Claim 2] The Cu-Ag alloy wire according to claim 1, wherein the product of the average diameter (nm) of the Ag phase and the average grain size (nm) of the matrix phase, measured in the cross-section, is less than 60 times the Ag content (mass%) in the Cu-Ag alloy wire. [Claim 3] The Cu-Ag alloy wire according to claim 1 or 2, further containing at least one component selected from the group consisting of Sn, Mg, Zn, In, Ni, Co, Zr, and Cr, each in an amount of 0.05 to 0.30% by mass. [Claim 4] The Cu-Ag alloy wire according to claim 1 or 2, wherein the Cu-Ag alloy wire is a round wire having a wire diameter of 0.01 mm to 0.08 mm. [Claim 5] The Cu-Ag alloy wire according to claim 1 or 2, wherein the Cu-Ag alloy wire is a ribbon wire having a width of 0.02 to 0.32 mm and a thickness of 0.002 to 0.040 mm, and having a substantially rectangular cross-section.